Fill in each blank with the correct word from the lesson.

1. A _______ change produces one or more new substances with different properties from the original.
2. Chemical _______ are usually irreversible and always produce something new.
3. _______ converts carbon dioxide and water into glucose using light — a complex chemical change occurring in every green plant.
4. _______ is a series of chemical changes that break food molecules into simpler ones.
5. _______ burns fuels by reacting with oxygen to produce carbon dioxide and water, releasing energy.

Choose the best option for each question.

1. Which is a reliable sign of a chemical change?
   a) The substance meltsb) A new substance with different properties formsc) The substance dissolves in waterd) The substance changes shape
2. Which of these is a chemical change?
   a) Crushing a canb) Dissolving sugarc) Melting waxd) Burning paper
3. Why is burning wood irreversible?
   a) The wood cools downb) New substances (ash, smoke, gases) are formedc) The wood changes colour onlyd) The wood is cut into pieces

Write T for True or F for False in the brackets.

1. A new substance with different properties forms is one of the key concepts in the lesson on Chemical Changes.
2. The substance melts is the main topic of this lesson.
3. Burning paper is one of the key concepts in the lesson on Chemical Changes.
4. Crushing a can is the main topic of this lesson.

1. In your own words, explain what Chemical Changes means.
2. List two things you learned from this lesson on Chemical Changes.